When you write smart contracts in Solidity you will use modifier for each function that indicates accessibility for the functions.
How to check connection status of websocket?
In web application development, you’d face a moment that need to check websocket connection status.For example, you’d have a situation that your web backend needs to check if users are active in the browser. It’s as very simple as you just need to check websocket property WebSocket.readyState. It has 4 possible values; “CONNECTING”, “OPEN”, “CLOSING”, “CLOSE”. …
Introduction to Hyperledger
Hyperledger is recent promising project and DLT technology for blockchain adoption.
Ngrok for webhook testing.
When you develop your web applications, you will have situation to test 3rd party API integration in the local development environment. The tricky problem here is most of 3rd party APIs are callback based. In a word, most of 3rd party APIs send data/status as callbacks/webhook to original client. However when you wants to test …
Get tired from node-gyp error in npm install?
It’s really fucking that when you get node-gyp permission error installing npm packages. There is a trade-off.You can workaround by adding –unsafe-perm to the npm install command. You can install the package peacefully.
Oraclize in Solidity
Solidity naturally has several problems that is difficult to implement. One of the things is read off-chain data from smart contract.Let’s say, if I want to get ETH/USD price in real time from smart contract, we don’t have a way to get from outside of blockchain. Oraclize bridges between on-chain and off-chain data sources and …
Javascript VM mode in Remix
When you develop smart contracts in Remix, it’s fucking that every test transactions are dragging so much time. So even for simple smart contract, we have to take much time for just transaction validation and testing. Remix provides Javascript VM mode for the blockchain emulation.Javascript VM mode is just memory based “blockchain”. It has same …
Introduction to SSH (Secure Shell)
As a developer, SSH(Secure Shell) is everyday use when you work with remote server. Let’s see how SSH works, what is the public key and private key, what configuration we need on server side and local environment and the like.